• Journal of the Korean Society of Radiology
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• v.17 no.2
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• pp.249-255
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• 2023

In this study, radiation exposure doses were measured in the course of clinical practice of radiation workers, radiological technologists in the radiation-related worker group, and preliminary-radiological technologists who were classified as frequent visitors. Radiological technologists who worked in the radiation area of C University Hospital in Incheon for a year from January 2021 and 121 students who completed clinical practice at the same medical institution from July 1 to August 31 were the subjects of the study. The nominal risk factor based on ICRP 103 was used to evaluate the probability of side effects due to the exposure dose to the lungs, which are organs at risk of damage due to radiation exposure dose. During the clinical practice period, radiology students, who were classified as frequent visitors, had a surface dose of 0.98 ± 0.14 mSv and a deep dose of 0.93 ± 0.14 mSv. In other words, 6.7 per 1,000,000 for shallow dose and 6.4 per 1,000,000 for deep dose were found to have side effects due to exposure to the lungs. This is a value in terms of exposure dose in one year. Considering that the radiation (science) education course is 3 or 4 years, systematic management and attention to prospective radiation workers who are going to clinical practice are required, and the stochastic effect of radiation In relation to this, it is considered that it will be used as basic data for radiation safety management.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.305-305
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• 2023

수문조사기기 검정은 강수량, 수위, 유량 등과 같은 수문자료를 관측하는 수문조사기기가 대상지역의 수문상황을 정확하게 관측하는지를 검사하는 일련의 과정으로 「수자원의 조사 계획 및 관리에 관한 법률」 제12조에 법적 기반을 두고 있다. 검정 대상은 강수량, 수위, 유속, 유사량, 토양수분량, 증발산량, 증발량 측정기기 총 7종이며, 환경부장관으로부터 한강홍수통제소가 검정업무를 위임받고, 한국건설기술연구원과 한국수자원조사기술원이 위탁받아 운영중에 있다. 최근에는 증발산량, 토양수분량 및 유량 측정기기기 등이 첨단화되어 기존 검정 방식에 대한보완 및 신설에 대한 요구가 증가하고 있다. 특히, 유량 측정시 기존에 사용하였던 회전식 유속계는 ADCP(Acoustic Doppler Current Profiler) 유량측정기기로 대체되어 활용률이 2013년 24%에서2021년 67%로 약 2.8배 급격히 증가하였다. 하지만 수문조사기기 검정 관련 고시 내 ADCP에 대한검사방법 및 허용오차 등의 규정이 부재하여 수문조사기기의 검정 공백이 발생하는 등의 문제가 존재하고 있다. 이에 본 연구에서는 ADCP 운영 및 기술 현황, 현행 법령, 국외 사례 등을 검토하여 ADCP 유량측정기기의 검사방법 및 허용오차에 대한 방안을 제시하고자 한다. ADCP 검사방법은 총 5단계로 외관검사, 자가진단 검사, 온도센서 검사, 수심측정 검사, 유량비교측정 검사에 따라 검정을 실시한다. 첫 번째 외관검사시에는 기기 외관과 센서 등 물리적 손상을 점검하고, 두 번째 자가진단 검사에서는 센서 변환 매트릭스 값, 수신부 센서 테스트, RAM/ROM 테스트, 통신 테스트 등에 관한 정상값 산출 여부를 확인한다. 세 번째 온도센서 검사에서는 검증용 온도센서를 이용한 값과 ADCP에 부착된 온도센서 값과 차이를 확인하고 ±2℃초과시 재검사 또는 적절한 조치를 취한 후 다음 단계의 검사를 진행한다. 네 번째 수심측정 검사에서는 수조 내 수심 측정을 확인하여 실제 수심과의 오차를 확인하고 ±1% 초과시 재검사 또는 적절한 조치 후 다음 검사를 실시한다. 유량비교 측정검사에서는 각 기기 간의 평균유량의 상대오차를 평가하는 것으로 ±5%미만에는 합격, ±5이상 ±10%미만에서는 재검사, ±10%이상에서는 공장수리를 권고하도록 하고, 1~5 단계의 검사를 통과한 기기를 대상으로 인증서를 발급하도록 한다. 유량비교 측정검사시에는 매년 ADCP를 사용하는 일반기업 및 공공기관 등이 모여 ADCP의 성능을 상호간 비교하는 'ADCP 기술협력 워크숍'을 확장하여 실시할 수 있다. 각 검사 단계의 허용오차는 USGS 또는 제조사 기준과 2022년 ADCP 기술협력 워크숍 성능검사 분석 결과를 토대로 하였다. 본 ADCP 검정 방안은 향후 ADCP 모델별로 단계별 시범 검토를 통해 세부사항에 대한 제시가 필요하며, 온도센서 검사, 수심측정 검사, 유량 비교측정검사에 대한 허용오차에 대한 타당성에대한 검증 및 검토가 이루어져야 할 것으로 사료된다.

• Journal of Life Science
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• v.34 no.8
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• pp.594-607
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• 2024

Plastic products have long been widely used in both industrial and household applications. However, tiny plastic particles derived from plastic products, such as microplastics (MPs) and nanoplastics (NPs), can infiltrate the human body through inhalation, ingestion, or skin contact. Once inside cells via endocytosis, MPs and NPs (MNPs) can trigger autophagy, but lysosomal dysfunction can block autophagic flux. Accumulating in the cytoplasm, these particles induce cellular stress, including oxidative stress from free radicals, mitochondrial dysfunction, and increased inflammatory response. Meanwhile, cellular senescence is a hallmark of aging and is defined as the stable termination of the cell cycle in response to cell damage and stress. In particular, the accumulation of oxidative stress, a key factor in inducing cellular senescence, induces the expression of major senescence markers. Senescent cells increase the secretion of senescence-associated secretory phenotype, including inflammatory cytokines and chemokines. Despite growing interest in how MNPs induce cellular senescence, there remains a gap regarding their onset and therapeutic targets. Therefore, this review focuses on identifying recent research trends on how MNPs induce cellular aging in key human cell types and proposes future research directions to overcome these challenges.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.395-402
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• 2014

BACKGROUND: Azadirachta indica Extract(AIE) containing azadirachtin as active ingredient have been used worldwide as environment-friendly organic material having pest control properties. However, the extracts prepared with different solvent and from different plant site is very diverse and have different toxicity. METHODS AND RESULTS: In this study, the four week repeated oral dose toxicity test of aqueous AIE in Sprague-Dawley rats was carried out to investigate the toxic effect of liver, main toxicity target organ of AIE. The male and female rats were divided into 4 groups, respectively; control(0 g/Kg bw), low-dose group(0.5 g/Kg bw), middle-dose(1.0 g/Kg bw) and high-dose group(2.0 g/Kg bw). As a results, relative liver weight increased with dose-dependent of AIE(p<0.05). Serum LDH in all AIE-treated groups were significantly lower than the control in male rats(p<0.05). However, serum GOT and GPT were significantly increased in all male AIE-treated groups in male rats(p<0.05) and, in particular, increase of serum GPT in dose-dependent manner raise the possibility of liver damage. Even through serum GLU was increased significantly in high-dose group in male rats compared to control, there were no significant differences of urinary GLU among all groups(p<0.05). In addition, histopathological examination of the liver did not reveal any lesions in all AIE-treated groups. CONCLUSION: In conclusion, 4 weeks of the repeated oral administration of AIE 2.0 g/Kg to rats has resulted no toxic response in liver. Therefore, AIE was no indicated to have any toxic effect in the SD rats, when it was orally administrated below the dosage 2.0 g/Kg/day for 4weeks.

• Clinical and Experimental Pediatrics
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• v.49 no.12
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• pp.1296-1300
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• 2006

Purpose : We studied the usefulness of transcutaneous bilirubinometers in follow-up of bilirubin levels during phototherapy in neonatal jaundice patients. Methods : Transcutaneous bilirubin (TcB) was measured twice per day on 90 neonatal jaundice patients without risk factors of jaundice by transcutaneous bilirubinometer JM-103(Minolta/Hill-Rom Air-shields, Japan). TcB was measured simultaneously on the patched-forehead (TcB-PF), patchedchest(TcB-PC), unpatched-forehead (TcB-UF) and unpatched-chest (TcB-UC) of infants with neonatal jaundice. Plasma bilirubin (PB) was measured by American Optical bilirubinometer (American Optical Co, Buffalo, USA) within 30 minutes after transcutaneous bilirubinometer measurement. Each TcB was compared with PB. Results : In the study group, the mean gestational age was $38.6{\pm}1.3wk$, the mean birthweight was $3,207.0{\pm}472.1g$, the mean age at start of phototherapy was $4.9{\pm}0.9days$ and the mean duration of phototherapy was $1.3{\pm}0.6days$. The correlation between TcB and PB level was observed. The correlation between TcB of the patched part (TcB-PF, TcB-PC) and PB was more significant than that of the unpatched part (TcB-UF, TcB-UC) and PB. The most significant correlation was between PB and TcB-PC. Conclusion : TcB was useful in the follow-up of jaundice during phototherapy as well the screening of jaundice in neonatal jaundice patients. TcB of patched-chest area was the most reliable site in transcutaneous bilirubinometer examination in neonatal jaundice patients.

• Clinical and Experimental Pediatrics
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• v.46 no.1
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• pp.42-50
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• 2003

Purpose : The acute respiratory distress syndrome(ARDS), an acute form of severe alveolar-capillary injury evolving after a direct or indirect lung insult is thought to be a common cause of respiratory failure though not many clinical studies on the subject have been made yet. Methods : Between January 1992 and December 2001, we conducted a retrospective study on 33 children who fulfilled the definition of the ARDS recommended by the American-European Consensus Conference in 1994. Results : A total of 33 patients(20 boys and 13 girls) were selected. Their age ranged from 4 months to 12 years with seven children younger than 1 year. The overall mortality rate was 78.8% and no significant difference was noted based on age or sex. Concerning seasonal variation, incidence of the ARDS increased in spring, especially in May(21.2%). Pneumonia(66.7%) was found to be the most common risk factor of the ARDS followed by sepsis(24.2%) and aspiration(3.0%). In immune compromised children(six cases), including a recipient of bone marrow transplantation, the mortality rate was 100%. Compared with children with multiple organ failure recording a 83.3% mortality rate, those with isolated respiratory failure, showed a lower mortality rate of 33.3%, although stastistically insignificant. Between survivor and non-survivor groups, significant differences were shown in hematocrit, $PaO_2$, $PaCO_2$, PEEP, and $PaO_2/FiO_2$ on the seventh day after the onset of the ARDS. Conclusion : According to our study, respiratory failure proved to have a great effect on mortality rate in the ARDS. More aggressive intervention and further studies on this subject should be done to improve the survival rate.

• Bulletin of the Society of Naval Architects of Korea
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• v.61 no.1
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• pp.16-29
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• 2024

2014년 4월 18일 오전 8시 48분경 전라남도 병풍도 인근 해역에서 세월호는 전복된 후 침몰하였다. 사고 당시 이 배에는 승객 443명과 선원 및 승무원 33명 모두 476명이 타고 있었고, 이 중 미수습자 5명을 포함하여304명이 생명을 잃었다. 그 동안 공식적인 사고원인 규명활동이 꾸준히 진행되어 이 사고의 원인을 규명하기 위한 조사가 네 차례 있었다. 하지만 아직까지 사고 원인이 무엇인지 명쾌하게 밝혀지지 않고 있다. 이 글에서는 먼저 그동안 있었던 네 차례의 공식적인 세월호 사고원인 규명활동을 정리하였다. 가장 먼저 사고원인 규명활동을 전개한 해양안전심판원 특별조사부는 2014년 사고 직후부터 그해 12월까지 활동하였다. 특별조사부 최종보고서에는 화물의 과적과 평형수 적재 부족으로 인한 선박복원성 기준 미달, 타각의 대각도 조타와 장시간 유지로 인한 부적절한 조타, 화물의 부실한 고박으로 인한 화물의 이동, 수밀문의 관리 부실로 인한 조기 침수와 비상대피장소(muster station)로의 승객대피 조치 미이행을 사고의 원인으로 들고 있다. 2015년 3월부터 2016년 6월까지 활동한 4·16세월호참사 특별조사위원회(특조위)는 '4·16 세월호 참사 특별 조사위원회 청산 백서'만을 간행하고 최종보고서를 제출하지 못한 채 활동을 종료하였다. 세월호 선체조사위원회(선조위)는 2017년 4월부터 2018년 8월까지 활동하였다. 선조위는 세월호 사고원인 규명을 위한 다른 기구에 비해 위원의 구성도 균형이 있었고, 직권사건 위주의 조사방법도 적절하였다. 또한 조타기와 조타 과실 여부, 급선회 항적 및 횡경사와 핀안정기의 물리적 손상에 관한 용역을 국내 여러 기관에 발주하였다. 뿐만 아니라 다양한 해양사고 원인규명 용역에 참여한 실적이 있는 영국의 기술용역회사인 Brookes Bell에 급선회와 빠른 침몰의 원인 조사를 요청하였다. 아울러 세계에서 가장 활발히 수조실험을 수행하고 있는 상업 연구소인 네덜란드의 MARIN에 수조시험과 시뮬레이션도 의뢰하였다. 하지만 아쉽게도 선조위는 서로 다른 사고 원인을 주장하는 두 권의 종합보고서를 간행하였다. 종합보고서로 '내인설' 종합보고서[6]는 타기 솔레노이드 밸브의 고착으로 시작된 급선회를 사고의 직접 원인으로 지목하고 있다. 하지만 '열린안' 종합보고서[7]에서는 수중체와의 충돌을 직접적인 사고 원인으로 밝히고 있다. 마지막으로 가습기살균제 사건과 4·16세월호 참사 특별조사위원회(사참위)가 2019년 3월부터 2022년 9월까지 활동하였다. 사참위는 위원으로 조선해양공학과 항해학 전문가가 포함되어 있지 않아 세월호의 사고원인 규명활동을 효과적으로 수행하기에는 적절하지 못하였다. 사참위는 주로 조타장치 고장에 따른 세월호 전타 선회현상 검증, 세월호 변형 손상부의 확인 및 원인 조사와 세월호 횡경사 원인과 침수과정 분석을 직권 과제로 추진하였다. 또한 네덜란드 MARIN에 자유항주시험을 추가로 의뢰하였으며, 핀란드의 NAPA group에도 복원성 계산과 침수해석을 의뢰하였다. 사참위는 선조위의 두 가지 사고원인에 대해 '내인설'의 솔레노이드 밸브 고착은 사고원인일 가능성이 매우 낮고, '열린안'의 수중체와의 충돌 시나리오는 근거가 부족함을 확인하였다. 이상에서 정리한 바와 같이 규명활동이 진행됨에 따라 사고원인이 수렴되어야 함에도 불구하고 아직까지 원인을 시원하게 밝히지 못하고 있다. 이 글에서는 사고원인 규명활동을 수행한 네 개 기구의 구성과 활동 내용을 비교하고, 사고조사 위원회의 바람직한 구성과 위원회의 운영 방법을 제시하고 있다. 또한 Brookes Bell 보고서에 수록된 출항 당시의 흘수에 근거한 배수량과 선미 램프의 폐쇄 전후의 횡경사각으로부터 도출한 GoM도 소개하고 있다. 아울러 출항 당시의 GoM값으로 추정한 사고 당시의 GoM값도 소개하고 있고, 수중체와의 충돌 시나리오를 후보 사고 시나리오에서 제외시켜야 할 이유도 열거하고 있다. 끝으로 해양사고 원인규명 활동이 보다 과학적으로 그리고 보다 합리적으로 이루어질 수 있기 위해 그리고 우리 사회의 안전문화 제고를 위한 몇 가지의 방안을 제시하고 있다. 또한 세월호 사고로 치른, 아직도 치르고 있는 희생을 딛고 해양안전문화가 한 걸음 더 나아가기 위해서는 세월호 사고의 원인을 반드시 규명해야 한다는 말씀으로 글을 마무리하고 있다.

• Radiation Oncology Journal
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• v.10 no.1
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• pp.1-6
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• 1992

The usefulness of hyperthermia for cancer therapy has been established. The purpose of the present investigation was to access feasibility of heating normal lung and the temperature and power requirement were compared with that for liver as solid organ in rabbits by using radiofrequent heating machine. In this study, 20 rabbits were divided into 2 groups according to the heating site and the method of temperature measurement; in group I : lung heating and temperature measuring in skin, esophagus and lung parenchyme; in group II : liver heating and temperature measuring in skin and liver parenchyme. The results were as follows; 1) When the maximum temperature was almost same in lung heating group and liver heating group, the power for liver heating was lesser required than the power for lung heating (p<0.05). 2) The temperature of esophagus for the measurement of mediastinum temperature was $1.1{\pm}0.9^{\circ}C$ higher than the temperature of lung parenchyme (p<0.05). Therefore the above findings suggest lung, air containing organ, is well heated as same as liver, solid organ. So more active trials of lung heating in the lung cancer must be likely considered. But when the lung is heated, the esophageal temperature is higher than lung parenchyme, so the mediastinum damage must be considered seriously.

• KDI Journal of Economic Policy
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• v.13 no.1
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• pp.35-63
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• 1991

Currently, Korea's banking industry holds a sizable amount of non-performing loans which stem from the government-led bailout of many troubled firms in the 1980s. Although this burden was somewhat relieved with the aid of banks' recapitalization in the booming securities market between 1986-88, the insolvent credits still resulted in low profitability in the banking sector and have been detrimental to the progress of financial liberalization and internationalization. This paper surveys the corporate bailout experiences of major advanced countries and Korea in the past and derives a rationale for readjustment measures against non-performing loans, in which rescue plans depend on the nature of the financial system. Considering the features of Korea's financial system and the banking sector's recent performance, it discusses possible means of liquidation in keeping with the rationale. The conflict of interests among parties involved in non-performing loans is widely known as one of the major constraints in writing off the loans. Specifically, in the case of Korea, the government's excessive intervention in allocating credits has preempted the legitimate role of the banking sector, which now only passively manages its past loans, and has implicitly confused private with public risk. This paper argues that to minimize the incidence of insolvent loan readjustment, the government's role should be reduced and that the correspondent banks should be more active in the liquidation process, through the market mechanism, reflecting their access to detailed information on the troubled firms. One solution is that banks, after classifying the insolvent loans by the lateness or possibility of repayment, would swap the relatively sound loans for preferred stock and gradually write off the bad ones by expanding the banks' retained earnings and revaluing the banks' assets. Specifically, the debt-equity swap can benefit both creditors and debtors in the sense that it raises the liquidity and profitability of bank assets and strengthens the debtor's financial structure by easing the debt service burden. Such a creditor-led or market-led solution improves the financial strength and autonomy of the banking sector, thereby fostering more efficient resource allocation and risk sharing.

• Journal of Chest Surgery
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• v.39 no.5 s.262
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• pp.387-393
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• 2006

Background: Esophageal perforation is an uncommon problem, but it is associated with high mortality. We performed a retrospective review of patients with instrumental esophageal perforation to assess the outcome of current management techniques. Material and Method: We retrospectively analyzed all cases of instrumental esophageal perforation diagnosed at our hospital from January 1999 through to March 2005. The study group consisted of 12 patients (8 women and 4 men) with a mean age of 48.8 years (range, $21{\sim}83$ years). We reviewed the effects of the surgical or medical treatments in various conditions of patients, such as of various sites of perforation and time delayed after injury. Result: Perforations were due to diagnostic endoscopy (50.0%, 6/12), esophageal bougination for benign stricture (33.3%, 4/12), endoscopic port insertion (8.3%, 1/12), and tracheal intubation (8.3%, 1/12). The perforated sites were thoracic in 7 patients and cervical in 5. The treatment included resection and reconstruction (5 cases), incision and drainage (4 cases), medical treatment (2 cases), and closed thoracostomy drainage only (1 case). Post-operative complications of transient pneumonia and wound infection were developed in 1 patient respectively. Both occurred in two patients with diffuse mediastinal abscess formation. The overall mortality was 8.3% (1/12) in one old patient who was managed medically for cervical esophageal perforation. Conclusion: We concluded that surgical treatment for esophageal perforations was safe and effective whether diagnosed early or lately.